Problem: $\begin{cases} f(1)=-8 \\\\ f(n)=f(n-1)-3 \end{cases}$ Find an explicit formula for $f(n)$. $f(n)=$
Solution: From the recursive formula, we can tell that the first term of the sequence is ${-8}$ and the common difference is ${-3}$. This is the explicit formula of the sequence: $f(n)={-8} {-3}(n-1)$ Note that this solution strategy results in this formula, however an equally correct solution can be written in other equivalent forms as well.